Enhancing the economic viability and sustainability of biomass-to-methanol process: Simulation-based optimization framework for process design and operation

Abstract

In this study, a simulation-based optimization framework was developed that systematically addresses process design, operating conditions, and external factors for biomass-to-methanol (BTM) processes. By developing the technology superstructure representing all possible conversion pathways for the BTM process, detailed process simulations of major unit processes were performed to obtain mass and energy data and cost information. Based on these simulation results, a mixed-integer linear programming optimization model was formulated to identify optimal process designs and operating conditions under two distinct objectives: biomass-to-MeOH aimed at maximum profit (BTMP) and biomass-to-MeOH aimed at maximum CO₂ reduction (BTMC). The BTMP process achieved a unit production cost (UPC) of 0.47 $/kg, net CO₂ equivalent emissions (NCE) of 0.96 kgCO_2eq/kg, carbon efficiency of 55 %, and energy efficiency of 49 %. The BTMC process resulted in superior environmental performance with NCE of 0.59 kgCO_2eq/kg, carbon efficiency of 86 %, and energy efficiency of 59 %, but higher costs (UPC: 0.58 $/kg). Scenario-based analysis of key external factors—including biomass type, H₂ price, carbon intensity of supplementary H₂, and carbon tax —revealed four distinct optimal solutions for BTMP and three for BTMC processes under varying market conditions. This framework provides quantitative guidance for implementing economically viable and environmentally sustainable BTM processes across diverse regional contexts and market conditions.